1. Technical Field of the Invention
The present invention relates to a telecommunications network and, in particular, to the interception of originating and terminating call connections within an Intelligent Network (IN) based telecommunications network.
2. Description of Related Art
With the promulgation of the Communications Assistance for Law Enforcement Act (CALEA) on Oct. 25, 1994, each telecommunications carrier (service provider) "shall ensure that its equipment, facilities, or services that provide a customer or subscriber with the ability to originate, terminate, or direct communications are capable of (1) expeditiously isolating and enabling the government, pursuant to a court order or other lawful authorization, to intercept, to the exclusion of any other communications, all wire and electronic communications carried by the carrier within a service area to or from equipment, facilities, or services of a subscriber. . ." (47 U.S.C. .sctn. 1002). Accordingly, a telecommunications switch must enable a law enforcement agency to intercept a call connection effectuated for a particular associated subscriber. Such a capability further must be provided within four years from the date of enactment of the relevant Act (i.e., by October, 1998).
Reference is now made to FIG. 1 which is a block diagram of a telecommunications network illustrating a call screening of an incoming call connection in a conventional telecommunications switch. A calling party subscriber, such as a wireline calling party terminal 10, originates a call connection towards a particular called party subscriber 40 by dialing a directory number associated therewith. An originating telecommunications switch 20 serving the calling party subscriber then transmits a call setup signal, such as an Integrated Service Digital Network User Part (ISUP) based Initial Address Message (IAM) 50, utilizing the dialed directory number as the called party number and the directory number associated with the calling party subscriber as the calling party number. The IAM signal 50 is then transmitted over a connected Signaling System No. 7 (SS7) telecommunications network and delivered to a terminating switch 30 serving the called party subscriber 40. Responsive thereto, a circuit connection 60 capable of transporting voice and/or data is established between the originating switch 20 and the terminating switch 30.
A traffic control system (TCS) 70 associated with the terminating exchange 30, for example, extracts the received called party number from the IAM signal 50 and determines whether the subscriber associated with the extracted number needs to be monitored or screened. As an illustration, the called party number is compared against data stored at an associated register (R) 80. A match of the called party number to a number stored in the register 80 is indicative of the fact that the called party subscriber needs to be monitored by a particular law enforcement agency. An application module 90 responds to the match by effectuating a circuit or data communication link 110 with a law enforcement administration function (LEAF) 100 indicated in the register (R) 80 to monitor the call. The LEAF 100 is further provided with call identification information including the calling party directory number, called party directory number, the direction of the call, etc. Concurrently, another circuit connection is effectuated toward the called party subscriber 40. The associated called party terminal 40 is then alerted (with a ring) and a speech connection is established with the calling party subscriber 10. As a result, the connected LEAF 100 is able to intercept and to monitor the communication between the calling party subscriber 10 and the called party subscriber 40.
As illustrated above, monitoring in a conventional switch requires that called party directory numbers for all incoming call connections and calling party directory numbers for all outgoing call connections effectuated through that particular switch are reviewed and evaluated against the data stored in the register (R) 80. This monitoring is extremely inefficient because very few subscribers are typically marked for law enforcement monitoring at any give time. As an illustration, for the city of New York, authorities have estimated that an average of five hundred twenty three (523) of the eighteen million subscribers within the city are marked for monitoring. Consequently, each and every call connections terminated toward and originated by the eighteen million subscribers need to be inefficiently screened in order to monitor the five hundred twenty three subscribers.
Even with the introduction of a new telecommunications architecture known as an Intelligent Network (IN), some of inefficiency and inconvenience in law enforcement agency monitoring still exist. Reference is now made to FIG. 2 illustrating an Intelligent Network (IN) 200 providing IN services. The basic concept behind IN is to move the intelligence out of each local exchange or Service Switching Point (SSP) 210 and to centralize the services providing the intelligence in a Service Control Point (SCP) 220. By centralizing the special subscriber services in the SCP 220, a new service can be added in only one place (i.e., the SCP) and provided to all subscribers connected to the multiple SSPs 210. Accordingly, one SSP 210 services multiple telecommunications subscribers or terminals 40, and one SCP 220 services multiple SSPs 210 or local switches. The interfaces between the SSPs 210 and SCPs 220 are established via links 240 utilizing Signaling System No. 7 (SS7) Transaction Capabilities Application Part (TCAP), or other Signaling Control Connection Part (SCCP) based application layer protocols. More specifically, Intelligent Network Application Protocols (INAPs) sit on top of the TCAP protocols to establish a control dialogue between the SSPs 210 and the SCP 220. Furthermore, in order to multiplex a plurality of SCPs 220 with a plurality of SSPs 210, a signal transfer point (STP) 230 is interfaced therebetween to properly route and to deliver data and signals. Signal links connected between an SSP 210 and a STP 230 are effectuated via dual links (e.g., 240A-240B). This is to ensure that when and if a first link or STP fails, another alternative route or node is still available for delivering signals to a designated SCP 220.
Utilizing the above architecture, an incoming or outgoing call connection is initially received by a serving SSP 210 associated with a particular subscriber terminal 40. Since the SSP 210 has no "intelligence" to determine what kind of call treatment should be applied toward the received call connection, the SSP 210 performs a query requesting call treatment instructions to the associated SCP 220 over the connected TCAP link 240.
In order to enable a serving SSP 210 to identify and to perform a query with an associated SCP 220, the directory number assigned to a particular IN subscriber needs to uniquely identify a particular SCP 220 as the serving SCP. As a result, each SCP 220 is pre-allocated with a series of directory numbers, such as a block of a thousand numbers from the NPA-NXX-XXXX number series. Subscribers are then associated with a particular SCP by assigning the pre-allocated directory numbers thereto. Thereafter, by maintaining such a one-to-one relationship between a particular IN subscriber and an SCP via the assigned directory number, the serving SSP 210 is able to identify and to query the correct SCP 220 for IN service. As an illustration, a first SCP 220A stores subscription data representing subscribers one through fifteen (1-15). A second SCP 220B similarly stores subscription data and provides IN services towards subscribers sixteen through thirty (16-30).
In response to an incoming call connection towards a particular subscriber, the serving SSP determines whether the called party subscriber is associated with an IN service. Such a determination is made by performing a B-number analysis on the indicated called party subscriber directory number. The resulting B-number analysis is then associated with data indicating whether the called party subscriber has a trigger activated for an IN category. If the subscriber is not associated with any trigger, an incoming call connection is allowed to be terminated directly towards the called party subscriber. On the other hand, when the called party subscriber has an IN trigger activated, the serving SSP 210 transmits a query signal towards an associated SCP 220. By transmitting the query signal utilizing the directory number associated with the subscriber as the destination address, the signal is properly routed to the associated SCP. The SCP 220, in turn, retrieves the relevant subscriber data, ascertains the appropriate subscriber service to be provided, and instructs the serving SSP 210 to effectuate the desired call treatment. Such instructions may, for example, instruct the serving SSP 210 to reject the call, forward the call to a forward-to-number, connect the call to voicemail, etc.
In order to effectuate a call interception within an IN telecommunications network as shown above, an existing IN trigger, such as a terminating service trigger, needs to be activated within a serving SSP. The serving SSP 210 then queries the associated SCP 220 for routing instructions. The SCP 220, in return, determines that the call needs to be intercepted and instructs the SSP 210 to intercept the received incoming call connection by establishing a circuit connection 110 with the LEAF 100.
Since the above described B-number analysis needs to be effectuated for each incoming call connection to identify the called party subscriber for each call, no redundancy or inefficiency as described in FIG. 1 exists within the IN based telecommunications network. However, such a configuration is still undesirable for a number of reasons. First, in order to ensure uniform interception procedures and services throughout a particular service area, such as a city or state, all SCPs 220 associated therewith need to be updated and maintained with the necessary Service Script Logics (SSLs), executable instructions and/or equipment. As an illustration, where the Federal Bureau of Investigation (FBI) needs to monitor a particular call connection using a different bearer (device) service, all associated SCPs within the coverage area need to be updated with new service logics and equipments. Such updating and maintenance operations are inconvenient.
Furthermore, service providers and associated telecommunications networks are independently operated and maintained. A request for monitoring and screening a particular subscriber therefore needs to be provided to a serving service provider and accordingly input into the associated SCP. Furthermore, numerous service provider employees and systems, such as a Service Management System (SMS), need to be involved in order to effectuate such a request in a conventional system. Not having an independent and consolidated control over associated call connections or communications, the access to the desired SCP 220 may not be convenient or confidential.
As a result, there is a need for a mechanism to efficiently and effectively monitor and intercept call connections within an IN based telecommunications network.